Continuing studies will assess the relative efficacies of vitamin D supplementation in doses of 2000 iu/day and 4000 iu/day vs 250H vitamin D 200 iu/day in reversing the decreased serum calcium and serum 250H vitamin D levels and the decreased bone mass measured by Cameron osteodensitometry in adult epileptics with anticonvulsant-induced osteomalacia. A study of the effect of vitamin D supplementation in the treatment of juvenile epileptics on the ketogenic diet regimen will be simultaneously undertaken, employing the above parameters and calcium balance studies. Animal model studies of the relative effectiveness of vitamin D, 250H vitamin D and 1,250H vitamin D in reversing the biochemical and histologic abnormalities of drug-induced osteomalacia will be continued. In addition the effects if acute and chronic treatment with anticonvulsant drugs the target tissue binding of intravenously administered 250HD-H3 and 1,250HD-H3 will be assessed. Continued efforts will be made to isolate, characterize and study the biologic actions of drug-induced liver microsomal vitamin D metabolites, employing silicic acid, sephadex LH-20, celite, and phenylhydroxyethyl sephadex LH-20 column chromatography. Finally, extensions of previous studies will assess the interrelation between steroid hormone alterations in vitamin D metabolism and the effects of anticonvulsant drugs, to further define situations which may alter the response of patients with anticonvulsant-induced osteomalacia to prophylactic therapy with vitamin D and its biologically active metabolites.